Low-cost radar with high-resolution imaging

• US 6,429,805 B1
• Filed: 04/18/2001
• Issued: 08/06/2002
• Est. Priority Date: 04/18/2000
• Status: Expired due to Fees

• Current Assignee: Thomson-CSF (Thales SA)
• Original Assignee: Thomson-CSF (Thales SA)
• Inventors: Tong, Dominique Lo-Hine, Cornic, Pascal, Laviec, Philippe
• Primary Examiner(s): Tarcza, Thomas H.
• Assistant Examiner(s): ANDREA, BRIAN K
• Application Number:
  US09/836,360
• Time in Patent Office: 475 Days
• Field of Search: 342/21, 342/39, 342/70, 342/123, 342/195-197, 342/368-376
• US Class Current: 342/70
• CPC Class Codes: G01S 13/88 Radar or analogous systems specially adapted for specific applications electromagnetic prospecting or detecting of objects, e.g. near-field detection, G01V3/00
• CPC Class Codes: G01S 13/89 for mapping or imaging
• CPC Class Codes: G01S 13/931 of land vehicles
• CPC Class Codes: G01S 7/032 Constructional details for solid-state radar subsystems
• CPC Class Codes: G01S 7/038 Feedthrough nulling circuits
• CPC Class Codes: G01S 7/352 Receivers
• CPC Class Codes: H01Q 21/0075 Stripline fed arrays H01Q21/065 takes precedence
• CPC Class Codes: H01Q 21/065 Patch antenna array
• CPC Class Codes: H01Q 3/26 varying the relative phase or relative amplitude of energisation between two or more active radiating elements; varying the distribution of energy across a radiating aperture H01Q3/12, H01Q3/22, H01Q3/24 take precedence
• CPC Class Codes: H01Q 3/2605 Array of radiating elements provided with a feedback control over the element weights, e.g. adaptive arrays
• CPC Class Codes: H01Q 3/2611 Means for null steering; Adaptive interference nulling

Abstract

A radar including a plurality of reception antennas corresponding to a plurality of homodyne reception channels, and a transmission antenna positioned with respect to the plurality of reception antenna such that a distance between the transmission antenna and each consecutive reception antenna of the plurality of reception antenna respectively increases from one reception antenna to the next. Also included is a beam-formation mechanism associated with the plurality of reception channels for receiving a reception signal from each of the homodyne reception channels. Further, a spacing between each reception antenna is set so as to orient a homodyne leakage in a direction located in an angular zone of space not processed by the radar.

Claims

1. A radar comprising:

a plurality of reception antennas corresponding to a plurality of homodyne reception channels;

a transmission antenna positioned with respect to the plurality of reception antennas such that a distance between the transmission antenna and each consecutive reception antenna of the plurality of reception antenna respectively increases from one reception antenna to the next; and

means for beam-formation by computation associated with the plurality of reception channels and for receiving a reception signal from each of the homodyne reception channels,

wherein a spacing between each reception antenna is set so as to orient a homodyne leakage in a direction located in an angular zone of space not processed by the radar.

2. The radar according to claim 1, wherein the distance from the transmission antenna to the reception antennas increases regularly from one reception antenna to the next one.

3. The radar according to claim 2, wherein the reception antennas corresponding to the reception channels are aligned with a substantially constant space between two consecutive reception antennas.

4. The radar according to claim 1, wherein the transmission antenna is aligned with the reception antennas.

5. The radar according to claim 1, wherein the homodyne leakage is used to perform a self-test of a transmission/reception faction of the radar.

6. The radar according to claim 1, wherein each reception channel further comprises a microwave mixer, an amplifier and an analog-digital converter, and

wherein a corresponding reception antenna is connected to a first input of a corresponding mixer, a second input of the corresponding mixer receives a signal produced by a local transmission oscillator, an output of the corresponding mixer is connected to the input of a corresponding amplifier, an output of the corresponding amplifier is connected to an input of a corresponding analog-digital converters and the corresponding analog-digital converter converts a reception analog signal into a digital signal designed to be processed by the means for beam-formation by computation.

7. The radar according to claim 6, wherein the reception antennas are patch type antennas made on one and the same printed circuit.

8. The radar according to claim 7, wherein the mixers are made on said same printed circuit.

9. The radar according to claim 6, further comprising:

a metal band surrounding the mixers, said metal band being cut at places in which microwave connection lines pass towards the reception antennas; and

a metal cover covering the mixers with edges of the metal cover in contact with the metal band.

10. The radar according to claim 1, wherein a waveform transmitted by the transmission antenna is of the FMCW type, a continuous waveform whose frequency is modulated in ramps.

11. The radar according to claim 1, wherein a waveform transmitted by the transmission antenna is of the frequency-hopping type.

12. The radar according to claim 1, further comprising a local oscillator for powering the transmission antenna and the reception channels.

13. The radar according to claim 12, wherein a microwave line length between the local oscillator and a respective mixer is the same for all the mixers.

14. The radar according to claim 6, wherein, with the printed circuit being fixed to a face of a plate, the other face of the plate supports the means for beam-formation by computation.

19. The radar according to claim 1, further comprising a shaft around which the radar rotates to sweep an interior of a container containing a material, the reception and transmission antennas being located so as to face the material.

20. The radar according to claim 1, further comprising an imaging function.

21. The radar according to claim 7, further comprising:

a metal band surrounding the mixers, said metal band being cut at places it which microwave connection lines pass towards the reception antennas, and

a metal cover covering the mixers with edges of the metal cover in contact with the metal band.

15. A modular radar comprising:

a radar including,

a plurality of reception antennas corresponding to a plurality of homodyne reception channels,

a transmission antenna positioned with respect to the plurality of reception antennas such that a distance between the transmission antenna and each consecutive reception antenna of the plurality of reception antenna respectively increases from one reception antenna to the next, and

means for beam-formation associated with the plurality of reception channels and for receiving a reception signal from each of the homodyne reception channels,

wherein a spacing between each reception antenna is set so as to orient a homodyne leakage in a direction located in an angular zone of space not processed by the radar, and

wherein circuits included in the means for beam-formation by computation operate in parallel.

16. The modular radar according to claim 15, wherein a first module functions as a driver module, a local oscillator of the first module controls all other modules, and each module includes an amplifier at an input to amplify a signal of the local oscillator.

17. The modular radar according to claim 15, wherein an output of the amplifier for the local oscillator signal which is fed into reception circuits of the driver module also enters an input of a power circuit of a second module.

18. The modular radar according to claim 15, wherein a transmission antenna is included in the driver module, and is fed by the local oscillator of the driver module.

22. The modular radar according to claim 15, further comprising a shaft around which the radar rotates to sweep the interior of a container containing a material, the reception and transmission antennas being located so as to face the material.

23. The modular radar according to claim 15, further comprising an imaging function.

24. A radar comprising:

a plurality of reception antennas corresponding to a plurality of homodyne reception channels;

a transmission antenna positioned with respect to the plurality of reception antennas such that a distance between the transmission antenna and each consecutive reception antenna of the plurality of reception antenna respectively increases from one reception antenna to the next; and

a beam-formation computational circuit associated with the plurality of reception channels and configured to receive a reception signal from each of the homodyne reception channels,

wherein a spacing between each reception antenna is set so as to orient a homodyne leakage in a direction located in an angular zone of space not processed by the radar.

25. The radar according to claim 24, wherein the distance from the transmission antenna to the reception antennas increases regularly from one reception antenna to the next one.

26. The radar according to claim 25, wherein the reception antennas corresponding to the reception channels are aligned with a substatially constant space between two consecutive reception antennas.

27. The radar according to claim 24, wherein the transmission antenna is aligned with the reception antennas.

28. The radar according to claim 24, wherein the homodyne leakage is used to perform a self-test of a transmission/reception function of the radar.

29. The radar according to claim 24, wherein each reception channel further comprises a microwave mixer, an amplifier and an analog-digital converter, and

wherein a corresponding reception antenna is connected to a first input of a corresponding mixer, a second input of the corresponding mixer receives a signal produced by a local transmission oscillator, an output of the corresponding mixer is connected to the input of a corresponding amplifier, an output of the corresponding amplifier is connected to an input of a corresponding analog-digital converter, and the analog-digital converter converts a reception analog signal into a digital signal designed to be processed by the beam-formation computational circuit.

30. The radar according to claim 29, wherein the reception antennas are patch type antennas made on one and the same printed circuit.

31. The radar according to claim 30, wherein the mixers are made on said same printed circuit.

32. The radar according to claim 29, further comprising:

a metal band surrounding the mixers, said metal band being cut at places in which microwave connection lines pass towards the reception antennas; and

a metal cover covering the mixers with edges of the metal cover in contact with the metal band.

33. The radar according to claim 24, wherein a waveform transmitted by the transmission antenna is of the FMCW type, a continuous waveform whose frequency is modulated in ramps.

37. The radar according to claim 29, wherein, with the printed circuit being fixed to a face of a plate, the other face of the plate supports the bear-formation computational circuit.

42. The radar according to claim 24, further comprising a shaft around which the radar rotates to sweep an interior of a container containing a material, the reception and transmission antennas being located so as to face the material.

43. The radar according to claim 24, further comprising an imaging function.

44. The radar according to claim 30, further comprising:

a metal band surrounding the mixers, said metal band being cut at places in which microwave connection lines pass towards the reception antennas; and

a metal cover covering the mixers with edges of the metal cover in contact with the metal band.

45. The modular radar according to claim 30, further comprising a shaft around which the radar rotates to sweep an interior of a container containing a material, the reception and transmission antennas being located so as to face the material.

46. The modular radar according to claim 30, further comprising an imaging function.

34. The radar according to clam 24, wherein a waveform transmitted by the transmission antenna is of the frequency-hopping type.

35. The radar according to clam 24, further comprising a local oscillator for powering the transmission antenna and the reception channels.

36. The radar according to claim 35, wherein a microwave line length between the local oscillator and a respective mixer is the same for all the mixers.

38. A modular radar, comprising:

a radar including,

a plurality of reception antennas corresponding to a plurality of homodyne reception channel,

a transmission antenna positioned with respect to the plurality of reception antennas such that a distance between the transmission antenna and each consecutive reception antenna of the plurality of reception antenna respectively increases from one reception antenna to the next, and

a beam-formation computational circuit associated with the plurality of reception channels and configured to receive a reception signal from each of the homodyne reception channels,

wherein a spacing between each reception antenna is set so as to orient a homodyne leakage in a direction located in an angular zone of space not processed by the radar, and

wherein circuits included in the beam-formation computational circuit operate in parallel.

39. The modular radar according to claim 38, wherein a first module functions as a driver module, a local oscillator of the first module controls all other modules, and each module includes an amplifier at an input to amplify a signal of the local oscillator.

40. The modular radar according to claim 39, wherein an output of the amplifier for the local oscillator signal which is fed into reception circuits of the driver module also enters an input of a power circuit of a second module.

41. The modular radar according to claim 39, wherein a transmission antenna is included in the driver module, and is fed by the local oscillator of the driver module.